Low cycle fatigue behaviour of additive manufactured maraging steel: Influence of build orientation and heat treatment

• Published in: Materials letters 2023-11, Vol.350, p.134943, Article 134943
• Main Authors: Vishwakarma, Jaydeep, Rajpurohit, R.S., Sudhakar Rao, G, Chattopadhyay, K., Santhi Srinivas, N.C.
• Format: Article
• Language: English
• Subjects: Additive Manufacturing; Build Orientation; Fatigue; Heat Treatment; Maraging Steel; Powder Bed Fusion using Laser Beam (PBF-LB)
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2023.134943

•Defect orientation affects fatigue; 90° samples had lowest life in ABM and HT conditions.•ABM showed cyclic softening; HT showed stable response with minor cyclic hardening.•Fracture surfaces reveal multiple crack initiation sites in both ABM and HT samples.•HT had less defects due to precipitation, LCF life was improved. The effect of build orientation and heat treatment (solution treatment and aging) on low cycle fatigue (LCF) behaviour of additive manufactured (AM) maraging steel, processed via powder bed fusion, using laser beam (PBF-LB) was investigated in the present work. The build orientation has significant influence on LCF behaviour of AM maraging steel. Un-melted defects were found to be the most detrimental to fatigue life. Defects in 90° oriented samples were more damaging than those in 45° and 0° oriented samples. Heat treatment (HT) of the AM maraging steel was found to be very effective in enhancing the fatigue life by 8–10 times due to marked strengthening by precipitation of intermetallic precipitates and reduction in size and number of AM defects. SEM fractography showedthat surface and interior flaws increased susceptibility to crack propagation through the cross-section.